1. Field of the Invention
The present invention relates to a photoreceptor for electrophotography and a process for manufacturing the same.
2. Description of Related Art
Those multi-layered organic photoreceptors which have been used heretofore as photoreceptors for electrophotography, generally have a structure comprising an electroconductive support, a carrier generation layer (CGL) formed on the support, and a carrier transport layer (CTL) formed on the carrier generation layer. There may be a case where an under coat layer (UL) is formed between the electroconductive support and the carrier generation layer, if necessary.
Materials to be used for the carrier generation layers include azoic materials and phthalocyanine based materials which are capable of generating charge carriers. Those carrier generation materials (referred to as CGM hereinunder) may be used in the form of dispersion in a binder such as polycarbonate resins and the like. Materials to be used for the carrier transport layers (i.e., carrier transport materials referred to as CTM by abbreviation) comprise a combination of hydrazone and the like capable of transporting charge carriers and a binder for enhancing mechanical strength. The under coat layers may be provided for improvement in accuracy of mechanical processing of the electroconductive supports as well as for preventing the carriers from leaking out of the carrier generation layer into the support. The under coat layers (referred to as UL hereinunder) may be formed on the electroconductive support as by a dipping technique where in general a polyamide resin is dissolved into an alcoholic solvent and then applied by dipping.
However, the UL should have a film thickness as thin as about 1 .mu.m for inhibition of a reduction in sensitivity. For this reason, the conventional dipping method has a technical difficulty in achieving such films. If the UL is not uniform in thickness and quality, electrical properties of the organic photoreceptor with the UL are uneven resulting in non-uniformity of images obtained. Therefore, there is a demand to form a uniform thin film over all the surface of the support which is not easy to achieve technically. Moreover, there is a need to use an apparatus equipped with antiexplosion means because solvents for dissolving the polyamide resins are alcoholic. In addition, the formation of the carrier generation layer on the UL requires to select deliberately such a solvents as not causing any elution of the materials out of the film so that the types of materials for use in the carrier generation layers and the carrier transport layers are limited.